Preliminarily investigating the promotion mechanism for the electrical and optical performance of transparent electrode with ITO/CuAg/Ag/ITO structure

Abstract

The electrical and optical properties of transparent electrodes with dielectric/metal/dielectric structure (TE-DMD) are the most important factors in flexible devices, which are directly related to the characteristics and long-term reliability of devices. In this work, the indium tin oxide (ITO) and CuAg/Ag films are selected as the dielectric and metal films. Then, the TE-DMDs consisting of ITO/CuAg/Ag/ITO structures are prepared onto the flexible ultra-thin glass substrate by magnetron sputtering technique, which thickness is 70 μm. With increasing the growth time of the CuAg/Ag layer, TE-DMDs with ITO/CuAg/Ag/ITO structures display better and better electrical and optical properties. XRD, XPS, SEM, and AFM measurements are carried out on the CuAg/Ag layers. The results show that Ag and CuAg display the face-centered cubic Ag structure. The atomic ratio of Cu/Ag in CuAg is about 3.05/96.95. Compared with Ag, Cu displays lower thermochemical electronegativity, which results in the easier formation of cross-linking coupling bonds between Cu and O at the ITO surface. With these cross-linking coupling bonds, the CuAg displays better nucleation density and uniformity on the ITO surface. So, with the CuAg interface layer, the following Ag could rapidly grow and form a continuous, dense, and uniform layer structure. Without the CuAg interface, the threshold thickness of the Ag layer is higher than 8 nm. while, with the CuAg interface, the threshold thickness of the Ag layer is reduced to lower than 5 nm.